2016 Gatlinburg Conference Poster
PS-53
Title: Profiles of Repetitive and Restricted Behavior in Individuals with Rare Genetic Syndromes Associated with Autism
Spectrum Disorder
Authors: Cristan Farmer, Audrey Thurm, Joan Han, Forbes Porter, Latha Soorya
Introduction: Repetitive and restricted behaviors (RRB) manifest in various forms, cutting across many syndromes and disorders.
However, there is growing support for the use of behavioral phenotypes to inform our understanding about the etiological
underpinnings of various disorders. With regard to genetic disorders associated with intellectual disability (ID), distinct
syndrome-specific profiles in repetitive behavior have been described (Moss, Oliver, Arron, Burbidge, & Berg, 2009). We add to
the literature by exploring profiles of RRB in rare genetic syndromes associated with intellectual disability and varying rates of
autism spectrum disorder (ASD): Smith-Lemli Opitz Syndrome (SLOS), Phelan-McDermid Syndrome (PMS), and WAGR Syndrome.
Methods: Individuals participating in syndrome-specific studies at NIH or were enrolled in a general screening protocol of
neurocognitive and behavioral phenotyping or a collaborating protocol at Mt. Sinai. An ASD diagnostic evaluation, including the
Autism Diagnostic Interview-Revised (ADI-R), was administered by expert clinicians. Participants were included in this report if
they had a valid ADI-R and were between the ages of 18 months and 24 years at the time of administration. We characterized
the profile of RRB using the Restricted, Repetitive, and Stereotyped Patterns of Behavior domain (Total C) of the ADI-R diagnostic
algorithm, obtained from 39 individuals with PMS (mean age, 7.4±4.5 years; mean Vineland-II composite, 52.2±13.1), 24 with
WAGR syndrome (mean age, 11.4±4.8 years; mean Vineland-II composite, 66.0±16.3), and 21 with SLOS (mean age, 12.0±5.9
years; mean Vineland-II composite, 59.4±18.6). The Total C score comprises four sub-domains: C1, Encompassing preoccupation
or circumscribed pattern of interest (two items, 4 points possible); C2, Apparently compulsive adherence to nonfunctional
routines or rituals (two items, 4 points possible); C3, Stereotyped and repetitive motor mannerisms (higher scored of two items,
2 points possible); and C4, Preoccupation with parts of objects or nonfunctional elements of material (higher scored of two
items, 2 points possible). C1 and C2 are often referred to as "higher-order" and C3 and C4 as "lower-order."
Results: Based on our full evaluation, the following proportions of each group met DSM-5 criteria for ASD: PMS, 77%; WAGR,
8%; SLOS, 24%. A high proportion of all genetic disorder groups met the autism threshold of 3 on the Total C score: PMS, 74%
(mean score = 4.18±2.27); WAGR, 71% (mean score = 3.25±1.73); SLOS, 81% (mean score = 4.05±2.16). For all groups, scores on
the higher-order subdomains were lower than scores on the lower-order subdomains, especially striking given the wider range
of possible scores on the higher-order subdomains. Between the groups, scores on subdomains C2 and C4 were very similar.
However, the WAGR group had a low score (0.38±0.71) on C1, compared to PMS (1.13±1.26) and SLOS (1.14±0.96). C3 scores
also varied across groups: PMS was highest (1.36±0.87), followed by WAGR (1.00±0.93) and SLOS (0.71±0.96). Detailed profiles
of these symptoms within these domains will be displayed, and compared against age and IQ ranges and ASD classifications in
each group.
Discussion: These results indicate that profiles of repetitive and restrictive behavior differ among the three genetic disorders
studied here, consistent with results showing disparities in these symptoms in other genetic disorders studied by Moss et al.
(2009).
References/Citations:
• Moss, J., Oliver, C., Arron, K., Burbidge, C., & Berg, K. (2009). The prevalence and phenomenology of repetitive behavior
in genetic syndromes. Journal of autism and developmental disorders, 39(4), 572-588.